Plastic Media Research Articles

Study of techniques improving the Domestic Wastewaters Treatment

The purpose of this article was to show the treatment capacity of bioreactors and their purification performance regarding the improvement of oxygen transfer by removing dissolved matter and suspended solids from domestic wastewater. For this purpose, three sets of tests were performed: Bacteria Adaptation in an aerated biological filter, Adsorption/Biosorption in anon-aerated Biological Filters and percolation in a trickling filter with three packed plastic media for evalued their performance. The results showed that for the adaptation tests DO concentration varied between 0.2 and 9 mg / L, which allowed a good aeration in the bioreactor. The removal performances of the organic material was 96.9% with an initial COD of 3200 mgO 2 /L, the turbidity has reached an abatement rate of 97.4% with an initial value of 625 NTU. For the Adsorption/Biosorption tests in a non-aerated Biological Filter, the performances of COD and turbidity reached a yield between 24 and 61%. For percolation, the yields found varied between 41 and 68% for the COD and turbidity. The OD concentration for his two tests varied from 0.2 to 1 mg/L. These results showed the use of several wastewater treatment techniques in a bioreactor.

Public Perception of Plastic Surgery in Saudi Arabia.

The general public perceives plastic surgeons as cosmetic surgeons. This study aimed to assess the general public's awareness of the field of plastic and reconstructive surgery in Saudi Arabia. A short, anonymous, web-based survey was distributed to the public using SurveyMonkey as a platform. Participants were asked to choose the surgeon for managing 16 case scenarios, 11 of which were commonly managed by plastic surgeons. In total, 2,116 participants completed the survey. The participants correctly chose plastic surgery as the specialty for managing 3 of the 11 listed plastic surgery case scenarios. More efforts are needed from plastic surgeons and media to educate the public about the scope of plastic and reconstructive surgery.

Mechano-Chemical Surface Modification of High-Speed Steel Cutting Tools

In this work, a mechano-chemical surface modification to improve cutting tool performance is proposed. We applied this surface modification via shot peening the rake faces of high-speed steel tools with a blend of Al2O3 and Cu2S particles that serve as a plastic deformation medium and a chemical precursor, respectively. Orthogonal cutting experiments under base oil lubrication demonstrated that the proposed treatment results in a reduction of cutting and thrust forces, as well as in a reduction of built-up edge formation. These effects are explained by favorable changes in the lubricity and roughness of the rake face, and they suggest that this method has the potential to increase cutting tool life, lower energy consumption, and improve the dimensional accuracy and surface quality of a machined workpiece.

Accelerated start-up of a partial nitritation-anammox moving bed biofilm reactor

The formation of anammox biofilm is a lengthy process, leading to reactor start-up times of several months even with addition of anammox inoculum. To demonstrate the effectiveness of combining bio-primer technique with seed carriers in further accelerating the start-up time of anammox reactors a pilot moving bed biofilm reactor was set-up at a dewatering facility of a municipal wastewater treatment plant. The reactor was filled to 40% with plastic media with a specific surface area of 402 m2 m−3 and was operated at 34 ± 1 °C. Using bio-primer coated media it was shown that a surface nitrogen removal rate of 2.5 g-N m-2 d-1 could be achieved in as little as 56 days. Free ammonia (FA) was thought to be the predominant inhibitor of nitrite oxidizing bacteria activity rather than the selective wash-out of nitrifying biomass. A minimum FA concentration of 2 mg NH3-N L-1 was suggested for optimal performance of partial nitritation and to prevent the build-up of nitrates. Biomass from the pilot reactor had developed a specific anammox activity of 19 ± 2 mg-N g-VSS-1 h-1 which was 75% higher than the seed biomass from an anammox-only reactor fed with synthetic wastewater.

Detoxification of Heterophase Wastes Using Controlled Gas-Contact Technologies

The methods of natural and forced supply and removal of gases in arrays of heterophase wastes of various nature used in controlled gas-contact detoxification technologies are considered. The classification of the main parameters of the waste is divided into groups – mechanical, filtration, temperature, chemical and biological. Based on the analysis of the parameters, generalized criteria for determining the scope of application of gas-contact technologies are proposed. The implementation of gas flow control technology is described, an example of which are complexes biothermal treatment of oil-contaminated soils. The main element of this complex is the combined aeration system, which is necessary to increase the rate of biochemical decomposition of hardly decomposable hydrocarbons in oil waste. The results of the experiment conducted in the framework of the calculation and design of the aeration system due to the insufficiency of the initial data are presented. Shown the need to create a general theoretical model of controlled gas flows in porous, water-saturated, hard plastic media, both in natural conditions and under the action of an artificial pressure drop.

РЕШЕНИЕ ЗАДАЧИ О РАСШИРЕНИИ СФЕРИЧЕСКОЙ ПОЛОСТИ В СРЕДЕ С УСЛОВИЕМ ПЛАСТИЧНОСТИ МОРА - КУЛОНА - ТРЕСКА

An analytical solution of the one-dimensional problem of a spherical cavity expanding at a constant velocity from a point in a space occupied by a plastic medium has been obtained. Impact compressibility of the medium is described using linear Hugoniot's adiabat. Plastic deformation obeys the Mohr - Coulomb yield criterion with constraints on the value of maximum tangential stresses according to Tresca's criterion. In the assumption of rigid-plastic deformation (the elastic precursor being neglected), incompressibility behind the shockwave front and the equality of the propagation velocities of the fronts of the plastic wave and the plane shockwave defined by linear Hugoniot's adiabat, a boundary-value problem for a system of two first-order ordinary differential equations for the dimensionless velocity and stress depending on the self-similar variable is formulated. A closed-form solution of this problem has been obtained in the form of a stationary running wave - a plastic shockwave propagating in an unperturbed half-space. This solution is a generalization of the earlier obtained analytical solution for a medium with the Mohr - Coulomb plasticity condition. The effect of constraining the limiting value of maximal tangential stresses on the distribution of dimensionless stresses behind the shockwave front has been examined. Formulas for determining the range of cavity expansion velocities, within which a simple solution for a medium with Tresca's plasticity condition is applicable, have been derived. The obtained solution can be used for evaluating resistance to high-velocity penetration of rigid strikers into low-strength soil media.

АППРОКСИМАЦИЯ НАПРЯЖЕНИЙ В ОКРЕСТНОСТИ ПОЛОСТИ, РАСШИРЯЮЩЕЙСЯ С ПОСТОЯННОЙ СКОРОСТЬЮ В СРЕДЕ С УСЛОВИЕМ ПЛАСТИЧНОСТИ МОРА - КУЛОНА

A one-dimensional problem of a spherical cavity expanding at a constant velocity from a point in an infinite elastoplastic medium is considered. The problem has a first-kind self-similar solution. Elastoplastic deformation of the soil is described based on Hooke's law and the Mohr-Coulomb yield criterion. An analytical solution of the problem in the elastic region contacting with the plastic yield region has been obtained. To determine stress and velocity fields in the plastic region, a known algorithm, based on the shooting method, of analyzing a boundary-value problem for a system of two first-order ordinary differential equations, including the fourth-order Runge - Kutta method, has been realized. An effective algorithm of numerically analyzing an expanding cavity problem, earlier proposed in the works by М. Forrestal et al., makes it possible to solve the problem accurately enough for practical applications. A formula for determining the critical pressure - the minimal pressure required for the nucleation, accounting for internal pressure of a cavity in the framework of the Mohr - Coulomb yield criterion, has been derived, which is a generalization of the earlier published solution for an elastic ideally plastic medium with Tresca's criterion. The obtained critical value was compared with a numerical solution in a full formulation at the cavity expansion velocities close to zero in a wide range of variation of the parameters of the Mohr - Coulomb yield criterion. It is shown that the inaccuracy of the approximation of the proposed formula does not exceed 6% for the variation of the internal friction coefficient all over the admissible range, and for the initial value of the yield strength increasing by three orders of magnitude.

Constitutive equations of the semi-microscopic theory of plasticity for a multiaxial stress state

A model of a plastic medium based on a plastic slip theory is presented in the paper. It is presumed that a micro-slip (i.e. a plastic shear) on any oriented plane occurs while a shear stress is exceeding some critical level at the same time with a rising of a local loading condition. In any other case a plastic shear does not occur.Under certain assumptions, one can integrate the increments of plastic shears over all possible slip planes in the case of an arbitrary three-dimensional stress state and obtain the constitutive relations for the plastic model, which is a version of the theory of plastic flow. For some particular loading paths in cases of two- and three-dimensional stress states ranges of orientation changes for slip planes are defined. Comparison between calculated plastic deformations and experimental ones is performed.

Development of mathematical models of plastic media for resource-saving metal systems technologies

Development of mathematical models of plastic media for resource-saving metal systems technologies

Performance and kinetics of algal-bacterial photobioreactor (AB-PBR) treating septic tank effluent.

Septic tank effluent contains high organic and nutrient contents. This study aimed to evaluate treatment performance of an algal-bacterial photobioreactor (AB-PBR) treating the septic tank effluent. The experimental unit employed a transparent plastic medium made from recycled drinking water bottles for attached-growth biofilm. Red LED lamp (light intensity ∼100 μmol/m2/s) was applied as an energy source for the growth of algal-bacterial biofilm in the AB-PBR. The experimental results showed that AB-PBR operated at the hydraulic retention time (HRT) of 3 days gave the highest chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) removal efficiencies of 64, 45 and 35%, respectively, by which the effluent COD concentrations could meet the effluent standards of Thailand, but the effluent TN and TP concentrations needed to be further removed. The Stover-Kincannon model was applied to determine the kinetic values of COD and TN removals with R2 values greater than 0.8. Microbiological examinations indicated Chlorella sp. is the predominant algal species growing in the AB-PBR, while the amplicon sequencing information analytical results revealed the bacterial phylum of Proteobacteria to be the predominant bacterial group.

Commentary on: An Analysis of Plastic Surgeons' Social Media Use and Perceptions.

Commentary on: An Analysis of Plastic Surgeons' Social Media Use and Perceptions.

Modeling of structural failure of Zircaloy claddings induced by multiple hydride cracks

Zirconium alloys have been serving as primary structural materials for nuclear fuel claddings. Structural failure analysis under extreme conditions is critical to the assessment of the performance and safety of nuclear fuel claddings. This work focuses on simulating structural failure of Zircaloy tubes with multiple hydride defects through modeling explicit crack propagation in ductile media. First, we developed an integrated cladding failure model by taking into account both crack initiation induced by hydride/matrix interface separation and ligament tearing-off between activated hydride cracks. Second, to accommodate the initiation, propagation, and coalescence of multiple cracks in finite plastic media we incorporated this structural failure model into a coupled continuous/discontinuous Galerkin (DG) based finite element code, a traditionally preferred implicit numerical framework. Third, to improve the adaptive placement of DG interface elements for crack propagation and to identify potential coalescence of cracks due to the interaction between adjacent hydride cracks, we defined a special failure index for the assessment of potential failure zones using both true plastic strain developed and predicted failure strain based on the Johnson–Cook material failure criterion. Finally, by calibrating the proposed material failure model using a cluster of Zircaloy material experimental tests, we successfully simulated a complete failure process of a fuel cladding tube with multiple hydride cracks.

The Problems in Terms of Stresses of Diffusion-Vortex Class in Infinite Rigid Viscoplastic Space

The statements and exact self-similar solutions of diffusion-vortex problems in terms of stresses simulating a nonstationary one-dimensional shear in some curvilinear orthogonal coordinate systems of a two-constant stiff-viscous plastic medium (Bingham body) are analyzed. Such problems include the diffusion of plane and axisymmetric vortex layers, as well as the diffusion of avortex filament. The shear occurs in regions of unlimited space expanding with time with a pre-unknown boundary, and a possible way of specifying an additional condition at infinity is described. A generalized vortex diffusion is introduced into consideration, containing a formulation with several parameters, including the order of the singularity peculiarities at zero. Self-similar solutions are constructed in which the order of the singularity corresponds to or does not correspond to the type of shift in the selected coordinate system.

An implicit discontinuous Galerkin finite element framework for modeling fracture failure of ductile materials undergoing finite plastic deformation

SummaryIt is a challenge to achieve a complete simulation of fracture failure in ductile materials undergoing large plastic deformation within implicit finite element frameworks due to instability issues. Currently, traditional nodal force or crack surface traction release methods target the direct release of tractions on cracked surfaces within the current time/load step. An abrupt change from a system without cracks to another system with cracks may contribute to the instability issues. Specifically, because of broken meshes, discontinuous Galerkin (DG) methods have an advantage over traditional continuous elements in naturally accommodating crack openings along DG interfaces across elements. To improve the convergence in nonlinear iterations during crack openings, we propose a relaxation scheme for DG formulations to gradually recover the traction‐free condition on cracked surfaces. Furthermore, this DG‐based relaxation scheme for crack openings in finite plastic media has been consistently formulated within the incomplete interior penalty DG framework. Finally, we have demonstrated a good performance of the proposed implicit DG formulation along with the DG relaxation scheme by successfully solving a nuclear fuel rod structural failure problem with multiple hydride crack openings and the Sandia Fracture Challenge benchmark.

MENINGKATKAN KREATIVITAS SENI MELALUI PELATIHAN MEMBUAT KARYA DENGAN MEMANFAATKAN BOTOL PLASTIK BEKAS

<p><em>The background of the activity is to integrate the educational curriculum in the Interior Design Study Program, in this case is the Basic Design course, and the Creative Experiments course, with the National Curriculum program in elementary school. Training activities using used plastic bottle media and acrylic paints are training to make Nirmana Dwimatra or 2 dimensional Designs that utilize </em><em>used goods</em><em>. Activity Nirmana 2 Matra is application to design elements, ie point, line, plane, color, and texture which is processed by applying certain design principles, such as harmony (Harmony), Rhythm, repetition (Repetition), unity (Unity ), balance (balance), and other design principles. This training activity is intended to train and provide insight to children of primary school age, so that they can be inspired and able to innovate on the 2-dimensional works that they already know. Creativity and innovative work can be one way to generate motivation in conducting teaching and learning activities.</em><em> </em><em>Through the Community Service of the Faculty of Art and Design Tarumanagara University, lecturers can provide training to create 2-dimensional work, which in turn is expected to provide benefits to teachers and students to give birth to new works better and more innovative. 2-dimensional work processing skills are very useful in supporting teaching and learning activities tailored to the needs of the National Curriculum materials, such as the work of color composition and the work of processing the form. In addition, the 2 dimensional work of the results of the training, the work of teachers, and the expected work of the students, are displayed in the classroom so as to beautify the class and provide a new atmosphere in the arrangement of the classroom.</em></p><p><em> </em></p><p><strong><em>Keywo</em></strong><strong><em>r</em></strong><strong><em>d</em></strong><strong><em>s</em></strong><em> :</em><em> </em><em>N</em><em>irmana dwimatra, creativity, curriculum.</em><em></em></p>

Finding Forces Required to Change Air Hammer Path in Soil

The authors solve the problem on forces required to change drilling path of air hammers in soil. Soil mass is assumed a rigid–plastic medium with the Mohr–Coulomb yield, and the air hammer deviator is considered as a nondeformable body. The problem is solved in two stages: introduction of the deviator in soil and travel of the air hammer in soil with the rear deviated at a certain angle. The loads applied to the rear, the forces and the moment required to changing the path of an air hammer in soil are calculated.

Biotrickling filtration of airborne styrene: A comparison of filtration media

ABSTRACTThis study compares the performances of fern and plastic chips as packing media for the biofiltration of a styrene-laden waste gas stream emitted in a plant for the manufacture of plastic door plates. Fern chips (with a specific surface area of 1090 m2 m−3) and plastic chips (with a specific surface area of 610 m2 m−3) were packed into a pilot-scale biotrickling filter with a total medium volume of 50 L for the performance test. Field waste gas with styrene concentrations in the range of 161–2390 mg Am−3 at 28–30 °C) was introduced to the bed and a fixed empty-bed retention time (EBRT) of 21 sec, a volumetric gas flow rate of 8.57 m3 hr−1, and superficial gas velocity of 53.6 m hr−1 were maintained throughout the experimental period. Nutrients containing metal salts, nitrogen, phosphorus, and milk were supplemented to the filters for maintaining the microbial activities. Results reveal that the biotrickling filter developed in this study had the highest styrene monomer (SM) elimination capacities (170 g m−3 hr−1 for fern-chip packing and 300 g m−3 hr−1 for plastic-chip packing) among those cited in the literature. The plastic medium is a favorable substitute for endangered fern chips. The thermal-setting nature of plastic chips limits their recycle and reuse as raw materials, and the study provides an opportunity for the utilization of the materials.Implications: Biotreatment of contaminants in air streams offers an inexpensive and efficient alternative to conventional technologies. Biofiltration has a great potential for the degradation of gas-borne styrene and total hydrocarbon (THC) removal efficiency of around 80%. The objective of this research was to compare the performances of fern chips and a kind of plastic chips as packing media for biofiltration of the styrene-laden waste gas stream emitted from cutting operations of stripes of premixed unsaturated polyester (UP) and styrene paste before hot-pressing operations for making plastic door plates. From a practical point of view, the plastic medium can be a good substitute medium for fern chips, which has been declared as a protected plant. This study provides an experimentally verified model for the design and operation of such biotreatment systems.

تکامل الأبعاد الجمالية والتعبيرية للوسائط التشکيلية لإثراء المشغولة الفنية متعددة المستويات

الملخص: وجدت الباحثة أن للوسائط التشکيلية (الخامات) دورا هاما في تکامل الأبعاد الجمالية والتعبيرية الخاصة بالمشغولة الفنية ذات المستويات المتعددة حيث يمکن لمختلف الوسائط التشکيلية مع تنوع الأساليب والتقنيات الأدآئية الخاصة بکل خامة على حدة أن تکون عاملا هاما متنوعا وملهما في مجال الأشکال الفنية وذلک بإختلاف الرؤى الفنية للممارس وبإختلاف الخامات أيضا على الرغم من ثبات الوسائط التشکيلية بکل عمل مشغولة فنية وذلک عن طريق تنظيم الأشکال وکيفية التأثير. يهدف البحث إلى الوصول إلى بعض التطبيقات العملية بالإفادة من الوسائط التشکيلية المختلفة (الخامات والتقنيات الخاصة بکل خامة على حدة کمصدر لتکامل الأبعاد الجمالية والتعبيرية للمشغولة الفنية متعددة المستويات). يتبع البحث المنهج الوصفي من حيث تناول أراء بعض الفنانين والنقاد عن الوسائط التشکيلية واهميتها بالنسبة للفنان والتعرف على ارتباطها بالتقنية ودورها في المشغولة الفنية، أما عن الإطار التطبيقى فيشمل إجراء تجربة تطبيقية على عينة من الطلاب للإفادة من الفکرة. وتشير نتائج البحث إلى أنه أمکن التوصل إلى حلول تشکيلية جديدة ومعاصرة للمشغولة الفنية متعددة المستويات من خلال تکامل الأبعاد الجمالية والتعبيرية للوسائط التشکيلية. Integrating Aesthetic and Expressive dimensions of Plastic media into Multi-level Artistic works Ayat Esmat AbdAllah Abdel Reheem Instructor of Handi Crafts Department of Art Education Faculty of Specific Education Ain Shams University The researcher found that the plastic media plays an important role in the integration of the aesthetic and expressive dimensions of the multi-level artistic works. The various plastic media, with a variety of methods and techniques, can be an important and varied factor in the field of art forms. This is in contrast to the technical visions of the practitioner and the difference in raw materials also, despite the stability of the plastic media in all the work of artistic busyness through the organization of shapes and how to influence. The research aims to reach some practical applications by utilizing various plastic media (raw materials and techniques for each material separately as a source of integration of the aesthetic and expressive dimensions of multi-level artistic works). The research follows the descriptive approach in terms of addressing the opinions of some artists and critics about the plastic media and its importance to the artist and the recognition of its relationship to technology and its role in the occupied art, while the application framework includes an experiment on the application of a sample of students to benefit from the idea. The results of the research indicate that it has been possible to reach new and contemporary artistic solutions for multilayered artistic works by integrating aesthetic and expressive dimensions of plastic media.

Condition for transition to an unstable state (necking) of a specimen in tension

On the stress-strain curve obtained in simple tension experiments, there is a region of instability due to the neck formation. In the theory of plasticity, conditions for the transition to an unstable state and appearance of the maximum point on the stress-strain diagram are determined. These condition were derived under the assumption of the material incompressibility. However, this assumption cannot be justified, since in the neck region, there are numerous damages (pores, micro-cracks), i.e., the material is compressible. With the current coefficient of lateral deformation, the authors formulate a condition for transition to an unstable state in a compressible plastic medium.

Simultaneous Treatment of Agro-Industrial and Industrial Wastewaters: Case Studies of Cr(VI)/Second Cheese Whey and Cr(VI)/Winery Effluents

Hexavalent chromium (Cr(VI)) was co-treated either with second cheese whey (SCW) or winery effluents (WE) using pilot-scale biological trickling filters in series under different operating conditions. Two pilot-scale filters in series using plastic support media were used in each case. The first filter (i.e., Cr-SCW-filter or Cr-WE-filter) aimed at Cr(VI) reduction and the partial removal of dissolved chemical oxygen demand (d-COD) from SCW or WE and was inoculated with indigenous microorganisms originating from industrial sludge. The second filter in series (i.e., SCW-filter or WE-filter) aimed at further d-COD removal and was inoculated with indigenous microorganisms that were isolated from SCW or WE. Various Cr(VI) (5–100 mg L−1) and SCW or WE (d-COD, 1000–25,000 mg L−1) feed concentrations were tested. Based on the experimental results, the sequencing batch reactor operating mode with recirculation of 0.5 L min−1 proved very efficient since it led to complete Cr(VI) reduction in the first filter in series and achieved high Cr(VI) reduction rates (up to 36 and 43 mg L−1 d−1, for SCW and WW, respectively). Percentage d-COD removal for SCW and WE in the first filter was rather low, ranging from 14 to 42.5% and from 4 to 29% in the Cr-SCW-filter and Cr-WE-filter, respectively. However, the addition of the second filter in series enhanced total d-COD removal to above 97% and 90.5% for SCW and WE, respectively. The above results indicate that agro-industrial wastewater could be used as a carbon source for Cr(VI) reduction, while the use of two trickling filters in series could effectively treat both industrial and agro-industrial wastewaters with very low installation and operational costs.